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Ch 6.3 - Standard Deviation and Z-score
Activity: Do Action! activity on page 278/279 #1-5
variance: the average squared difference of the scores from the mean
HW: page 275 #1, 3, 5, 9
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6.3February-24-153:00 PM
MDM4U Page 1
Problems with variance:more 'weight' is given to extreme (very large or small) values•gives units squared, which is different than the units of the data•
standard deviation: the square root of the variance; the average distance of the scores from the mean
Ex1 - Std Dev. in Graphs
Which graph has a greater standard deviation?
graph 1 graph 2
If the variation on graph 1 is 1.5, what is the std. dev.?
What would graph 1 look like if the standard deviation were 1.8?
MDM4U Page 2
What would graph 1 look like if the standard deviation were 1.8?
Ex 2 - Std Dev. from data
Find the mean and std. dev.1 2 3 4 2 1 2 4 2 3 3 3 4 1 1 2 3
What would to the std dev if the values were all 1 higher?
z-score: the number of std dev an observation is from the mean
Ex 3: z-score
A data set has a mean of 5 and a std dev of 1.2, determine the z-scores for data with values of 6.2 and 3.
MDM4U Page 3
HW: pg 286 #1, 2, 3, 4, 6, 7a
MDM4U Page 4